The aims of the current proposal are as follows: 1) To apply our initial isolation techniques of 2',3'-cyclic nucleotide 3'-phosphodiesterase (EC 3.1.4.37, CNP) from human and bovine brain to the isolation and characterization of both guinea pig and rat (mouse) CNP and to isolate sufficient antigen for immunizations, 2) To produce antibodies to both pure enzymes obtained above in New Zealand White rabbits or other suitable animal, 3) To use the appropriate antibodies obtained above for EM localization studies for CNP in the neurological mutant mice Quaking, Shiverer, and Jimpy and for high resolution EM localization of CNP in perfused guinea pig brain, particularly in myelin, 4) To determine the amino acid compositions of at least the pure guinea pig, rat, and rabbit CNP enzymes, and other sources of CNP as they are available, 5) To prepare, isolate, and characterize cyanogen bromide-cleaved peptide fragments of the purified bovine, rat, guinea pig, rabbit, and other CNP enzymes and to obtain at least partial amino acid sequence data, and 6) To compare the amino acid and partial sequence data of the CNP enzymes above to those available of the myelin-associated glycoprotein (MAG), proteolipid protein, myelin basic protein, and the major Wolfgram proteins. The proposed research will extend our initial experiments indicating that CNP is localized to the oligodendrocyte and will enable us to examine the distribution of CNP in normal guinea pig brain myelin and to determine the localization of CNP in affected neurological mutant mice and control animals (Shiverer, Quaking, and Jimpy) using antisera to the appropriate purified CNPs in two suitable readily perfusible experimental animals, mouse and guinea pig. Second, the studies on the amino acid composition and sequence of cyanogen bromide peptides prepared from pure CNPs will permit a clearer understanding of the possible relationships among CNP and the other myelin membrane proteins. The proposed studies should result in the production of suitable antibodies that would facilitate future studies in smaller readily perfusible animals such as rats, mice and guinea pigs in which myelin formation is arrested or in which there occurs a loss of myelin during development.